The dimension from the black, (top washer where the diverter screws into the faucet), seal to the bottom of the nylon internal seal is very critical since both places have to seal at the same time. If the black cap washer is a little too thick then the nylon one will not seal and you will get your leakage. Replacing the stem seal with a thick layer of teflon tape which will compress to the proper thickness usually cures the problem.

: I replaced the diverter stem in my Price Pfister 3-handle shower unit--twice. The first attempt was: with an aftermarket Danco diverter obtained at the local hardware store. However, it allowed water : to flow to the tub faucet when the shower was supposed to be in operation. Figuring that the Danco : diverter was less than superior quality, I went to a plumbing supply house and ask for the : Price Pfister diverter. The guy pulled one for me--unpackaged and brand unknown--and I figured : it ought to be the right one. Unfortunately, it has the same problem.

: So, I took a closer look at these two new diverters. I did a little measuring. On both the new: diverters, the internal seal (I'm not sure if that is what it is really called, but I hope it means: something to the readers) is a smaller diameter than the one on the original diverter. It isn't smaller: by much, but it is enough, I believe, to allow water to enter the tub-side of the diverter even: when the tub-side has been closed off. By the way, both new diverters do have the washer in place : that is supposed to seal off water going to the tub when the shower is on.